All electrical and electronic products sold in markets around the world must demonstrate that they function according to existing safety regulations and standards, as implemented in safety laws and codes. One area of safety regulation involves moving components of electronic devices. Moving components of electronic device must comply with safety regulations, for example safety standard IEC60950-1, incorporated by reference here.
Many electronic devices contain heat-generating components that require cooling. A variety of cooling solutions are employed to regulate the thermal environment of electronic devices. For example, electronic devices such as computers (e.g. desktops, laptops, workstations, etc.) employ heat sinks and/or cooling fans in order to cool specific heat generating components (e.g. a central processing unit, CPU) and to cool the overall device. Without such cooling, the electronic device and its components can overheat and be damaged.
A commonly employed cooling solution in electronic devices is provisioning of airflow by one or more fans, providing thermal regulation to the device and specific heat generating components of the electronic device. Fans generate the airflow required for cooling by rotating at a sufficient speed (peripheral blade speed).
When a fan is used in an electronic device, in addition to accomplishing the cooling job, it must also be configured to protect people from harm. Accordingly, all electronic device fans must demonstrate that they function according to existing safety regulations. The regulations vary based on geographic location, with different degrees of complexity. Accepted safety standards (i.e. IEC60950-1) currently require that fans with (peripheral blade) speeds over a certain predetermined limit (e.g. 15 meters/second (m/s)) have safety features.
Conventional safety features ensuring safety regulation compliance include a safety (finger) guard; reduced fan speeds; and use of specialized materials. However, each of these conventional safety features has significant drawbacks. Safety guards negatively impact thermal and acoustic performance characteristics of the fan. Reduced fan speeds have an obvious negative impact on the amount and quality of airflow produced. Finally, a fan fashioned out of a specialized material can be used (e.g. a specific Dshore hardness) but use of such specialized, safety compliant materials results in a much higher cost and is thus a rather unattractive solution.
The safety guard is widely employed yet has significant drawbacks when it comes to fan performance characteristics. For example, safety guards reduce the amount of airflow produced because they interfere with the airflow entering and/or exiting the fan arrangement inlet/exhaust, depending on where the safety guard(s) is placed. Thus, safety guards tend to increase the static pressure and reduce the amount of airflow provided by the fan. Additionally, safety guards are problematic in as much as they tend to create turbulence in the airflow entering and/or exiting the fan arrangement. This turbulence produced by the safety guards creates acoustic disturbances, propagating noise.
Thus, fans need to rotate at a certain speed in order to provide adequate cooling; however, the speeds required to provide adequate cooling in electronic devices often trigger the need for additional safety features, such as safety guards. In turn, the safety guards tend to cause problems such as reducing fan performance (e.g. in terms of airflow and noise production).
Accordingly, a need has arisen for a way to make moving components of electronic devices, such as fans, compliant with commonly accepted safety standards but that does not reduce the component's performance or increase its cost substantially.